This blog discusses current weather, weather prediction, climate issues, and other topics

Thursday, March 8, 2012

Lenticular Clouds

Spectacular Lenticular Cloud Downstream of Mt. Rainer taken by John Caldwell

A close up by John Caldwell:

My discussion of the weekend weather and lenticular clouds is found at KPLU: http://www.kplu.org/)

Today there were wonderful displays of lenticular clouds (a.k.a. mountain wave clouds) downstream of both the Olympics and Mt. Rainier. In addition to the stunning picture by John Caldwell shown above, I have included a few others for your viewing pleasure. First one from the cam on top of my building, facing towards the Olympics:

Or one downstream of Mt. Rainier, again from my building:

A far better picture taken by Kevin Freitas in Tacoma was found online at this website:

You could see these lenticular clouds from space as viewed in the high-resolution visible satellite photo right before sunset.

And here is one from Dale Ireland's famous cam in Silverdale:

Why do we get such features? They occur when air, often near saturation, approaches a mountain barrier. Pushed up by the mountains, the air goes into an oscillation, with the waves propagating both downstream and upward. Here is a schematic of the process:

The clouds are often lens shaped because that reflected the vertical velocity patterns produced by the mountains. And there are often multiple plates or disks when there is structure to the moisture profile.

To see what the air approaching our region looked like today, here is a vertical sounding at Quillayute, near the Washington coast at 4 PM today. Red is temperature and blue indicates dewpoint. The closer they are the near to saturation the air. The numbers of the left indicate pressure (500 is roughly 18K feet, 700 around 10K feet, etc). The air is close to saturation above 18K feet, with winds from southwest. Good situation for lenticular clouds.

Did the super-hi resolution WRF model (4/3 km resolution) simulate these clouds? You know the answer! Here is the simulated cloud field at 4 PM. You see a veil of high clouds with the mountain wave clouds embedded in them. Pretty impressive forecast (12 h ahead).

Finally, if some of you are VERY lucky you might sneak a peek of the aurora tonight...but its a race against the approaching clouds.

The TERRA satellite captured a nice image of the lenticular clouds at 12:40pm 8 March. I have noticed that lenticular formations over Mt Rainier always form a "V" shape in the satellite images.Image athttp://tinyurl.com/852veg6